Zonal Statistics Example¶
[1]:
import wradlib as wrl
import matplotlib.pyplot as pl
import matplotlib as mpl
import warnings
warnings.filterwarnings('ignore')
try:
get_ipython().magic("matplotlib inline")
except:
pl.ion()
import numpy as np
import xarray as xr
Setup Examples¶
[2]:
def testplot(ds, obj, col="mean",
levels=[0, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, 50, 100],
title=""):
"""Quick test plot layout for this example file
"""
colors = pl.cm.viridis(np.linspace(0, 1, len(levels)))
mycmap, mynorm = from_levels_and_colors(levels, colors, extend="max")
radolevels = [0, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, 50, 100]
radocolors = pl.cm.viridis(np.linspace(0, 1, len(radolevels)))
radocmap, radonorm = from_levels_and_colors(radolevels, radocolors,
extend="max")
fig = pl.figure(figsize=(10, 16))
# Average rainfall sum
ax = fig.add_subplot(211, aspect="equal")
obj.zdata.trg.geo.plot(column=col, ax=ax,
cmap=mycmap, norm=mynorm,
edgecolor="white", lw=0.5,
legend=True, legend_kwds=dict(shrink=0.5))
ax.autoscale()
pl.xlabel("UTM Zone 32 Easting")
pl.ylabel("UTM Zone 32 Northing")
pl.title(title)
pl.draw()
# Original radar data
ax1 = fig.add_subplot(212, aspect="equal")
pm = ds.plot(x="x", y="y", cmap=radocmap, norm=radonorm, ax=ax1,
cbar_kwargs=dict(shrink=0.5))
obj.zdata.trg.geo.plot(ax=ax1, facecolor="None", edgecolor="white")
pl.xlabel("UTM Zone 32 Easting")
pl.ylabel("UTM Zone 32 Northing")
pl.title("Original radar rain sums")
pl.draw()
pl.tight_layout()
Zonal Stats Rectangular Grid¶
[3]:
from matplotlib.collections import PatchCollection
from matplotlib.colors import from_levels_and_colors
import matplotlib.patches as patches
import datetime as dt
from osgeo import osr
[4]:
# check for GEOS enabled GDAL
if not wrl.util.has_geos():
print("NO GEOS support within GDAL, aborting...")
exit(0)
[5]:
# Read and prepare the actual data (RADOLAN)
f = wrl.util.get_wradlib_data_file(
'radolan/misc/raa01-sf_10000-1406100050-dwd---bin.gz')
ds = wrl.io.open_radolan_dataset(f)
[6]:
# create radolan projection osr object
proj_stereo = wrl.georef.create_osr("dwd-radolan")
# create UTM Zone 32 projection osr object
proj_utm = osr.SpatialReference()
proj_utm.ImportFromEPSG(32632)
# Source projection of the shape data (in GK2)
proj_gk2 = osr.SpatialReference()
proj_gk2.ImportFromEPSG(31466)
[6]:
0
[7]:
print(proj_gk2)
PROJCS["DHDN / 3-degree Gauss-Kruger zone 2",
GEOGCS["DHDN",
DATUM["Deutsches_Hauptdreiecksnetz",
SPHEROID["Bessel 1841",6377397.155,299.1528128,
AUTHORITY["EPSG","7004"]],
AUTHORITY["EPSG","6314"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4314"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",6],
PARAMETER["scale_factor",1],
PARAMETER["false_easting",2500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Northing",NORTH],
AXIS["Easting",EAST],
AUTHORITY["EPSG","31466"]]
[8]:
shpfile = wrl.util.get_wradlib_data_file(
'shapefiles/agger/agger_merge.shp')
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
print(f"Found {len(trg)} sub-catchments in shapefile.")
Found 13 sub-catchments in shapefile.
[9]:
print(trg.crs)
PROJCS["WGS 84 / UTM zone 32N",
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4326"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",9],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","32632"]]
[10]:
bbox = trg.extent
buffer = 5000.
bbox = dict(left=bbox[0] - buffer, right=bbox[1] + buffer,
bottom=bbox[2] - buffer, top=bbox[3] + buffer)
print(bbox)
{'left': 365059.5928799211, 'right': 419830.11388741195, 'bottom': 5624046.706676126, 'top': 5668055.540990271}
[11]:
# Get RADOLAN grid coordinates
x_rad, y_rad = np.meshgrid(ds.x, ds.y)
grid_xy_radolan = np.stack([x_rad, y_rad], axis=-1)
# Reproject the RADOLAN coordinates
xy = wrl.georef.reproject(grid_xy_radolan,
projection_source=proj_stereo,
projection_target=proj_utm)
# assign as coordinates
ds = ds.assign_coords({"xc": (["y", "x"], xy[..., 0], dict(long_name="UTM Zone 32 Easting", units="m")),
"yc": (["y", "x"], xy[..., 1], dict(long_name="UTM Zone 32 Northing", units="m"))})
ds_clip = ds.where((((ds.yc > bbox['bottom']) & (ds.yc < bbox['top'])) &
((ds.xc > bbox['left']) & (ds.xc < bbox['right']))), drop=True)
display(ds_clip)
<xarray.Dataset> Dimensions: (y: 48, x: 58, time: 1) Coordinates: * time (time) datetime64[ns] 2014-06-10T00:50:00 * y (y) float64 -4.234e+03 -4.233e+03 ... -4.188e+03 -4.187e+03 * x (x) float64 -214.5 -213.5 -212.5 -211.5 ... -159.5 -158.5 -157.5 xc (y, x) float64 3.66e+05 3.669e+05 3.679e+05 ... 4.184e+05 4.193e+05 yc (y, x) float64 5.623e+06 5.623e+06 ... 5.669e+06 5.669e+06 Data variables: SF (y, x) float32 nan nan nan nan nan nan ... nan nan nan nan nan nan Attributes: radarid: 10000 radolanversion: 2.13.1 radarlocations: ['asw', 'boo', 'emd', 'han', 'umd', 'pro', 'ess', 'drs',... radardays: ['asw 10', 'boo 24', 'drs 24', 'emd 24', 'ess 24', 'fbg ...
[12]:
###########################################################################
# Approach #1: Assign grid points to each polygon and compute the average.
#
# - Uses matplotlib.path.Path
# - Each point is weighted equally (assumption: polygon >> grid cell)
# - this is quick, but theoretically dirty
###########################################################################
t1 = dt.datetime.now()
# Get RADOLAN center grid points for each grid cell
# (MUST BE DONE IN NATIVE RADOLAN COORDINATES)
grid_x, grid_y = np.meshgrid(ds_clip.x + 0.5, ds_clip.y + 0.5)
grdpoints = np.dstack([grid_x, grid_y]).reshape(-1, 2)
src = wrl.io.VectorSource(grdpoints, srs=proj_utm, name="src", projection_source=proj_stereo)
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
# Create instance of type ZonalDataPoint from source grid and
# catchment array
zd = wrl.zonalstats.ZonalDataPoint(src, trg, srs=proj_utm, buf=500.)
# dump to file (for later use - see below)
zd.dump_vector('test_zonal_points_cart')
# Create instance of type ZonalStatsPoint from zonal data object
obj1 = wrl.zonalstats.ZonalStatsPoint(zd)
isecs1 = obj1.zdata.isecs # for plotting (see below)
t2 = dt.datetime.now()
t3 = dt.datetime.now()
# Create instance of type ZonalStatsPoint from zonal data file
# (much faster)
obj1 = wrl.zonalstats.ZonalStatsPoint('test_zonal_points_cart')
# Compute stats for target polygons
avg1 = obj1.mean(ds_clip.SF.values.ravel())
var1 = obj1.var(ds_clip.SF.values.ravel())
t4 = dt.datetime.now()
print("Approach #1 computation time:")
print("\tCreate object from scratch: %f "
"seconds" % (t2 - t1).total_seconds())
print("\tCreate object from dumped file: %f "
"seconds" % (t4 - t3).total_seconds())
print("\tCompute stats using object: %f "
"seconds" % (t3 - t2).total_seconds())
# PLOTTING Approach #1
src = wrl.io.VectorSource(grdpoints, srs=proj_utm, name="src", projection_source=proj_stereo)
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
# Just a test for plotting results with zero buffer
zd2 = wrl.zonalstats.ZonalDataPoint(src, trg, buf=0)
# Create instance of type ZonalStatsPoint from zonal data object
obj2 = wrl.zonalstats.ZonalStatsPoint(zd2)
# copy attributes to target layer
obj2.zdata.trg.set_attribute("mean", avg1)
obj2.zdata.trg.set_attribute("var", var1)
isecs2 = obj2.zdata.isecs
Approach #1 computation time:
Create object from scratch: 1.801533 seconds
Create object from dumped file: 0.081224 seconds
Compute stats using object: 0.000030 seconds
[13]:
# Illustrate results for an example catchment i
i = 6 # try e.g. 5, 2
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, aspect="equal")
# Target polygon patches
trg_patch = obj2.zdata.trg.get_data_by_idx([i], mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="black", linewidth=2)
trg_patch = obj1.zdata.trg.get_data_by_idx([i], mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="grey", linewidth=2)
# pips
sources = obj1.zdata.src.geo
sources.plot(ax=ax, label="all points", c="grey", markersize=200)
isecs1 = obj2.zdata.dst.get_data_by_att(attr="trg_index", value=[i], mode="geo")
isecs1.plot(ax=ax, label="buffer=0 m", c="green", markersize=200)
isecs2 = obj1.zdata.dst.get_data_by_att(attr="trg_index", value=[i], mode="geo")
isecs2.plot(ax=ax, label="buffer=500 m", c="red", markersize=50)
cat = trg.get_data_by_idx([i])[0]
bbox = wrl.zonalstats.get_bbox(cat[..., 0], cat[..., 1])
pl.xlim(bbox["left"] - 2000, bbox["right"] + 2000)
pl.ylim(bbox["bottom"] - 2000, bbox["top"] + 2000)
pl.legend()
pl.title("Catchment #%d: Points considered for stats" % i)
[13]:
Text(0.5, 1.0, 'Catchment #6: Points considered for stats')
[14]:
# Plot average rainfall and original data
testplot(ds_clip.SF, obj2, col="mean", title="Catchment rainfall mean (ZonalStatsPoint)")
[15]:
testplot(ds_clip.SF, obj2, col="var",
levels=np.arange(0, np.max(var1), 1.),
title="Catchment rainfall variance (ZonalStatsPoint)")
[16]:
###########################################################################
# Approach #2: Compute weighted mean based on fraction of source polygons
# in target polygons
#
# - This is more accurate (no assumptions), but probably slower...
###########################################################################
# Create vertices for each grid cell
# (MUST BE DONE IN NATIVE RADOLAN COORDINATES)
grid_x, grid_y = np.meshgrid(ds_clip.x + 0.5, ds_clip.y + 0.5)
grdverts = wrl.zonalstats.grid_centers_to_vertices(grid_x,
grid_y,
1., 1.)
# And reproject to Cartesian reference system (here: UTM Zone 32)
src = wrl.io.VectorSource(grdverts, srs=proj_utm, name="src", projection_source=proj_stereo)
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
t1 = dt.datetime.now()
# Create instance of type ZonalDataPoly from source grid and
# catchment array
zd = wrl.zonalstats.ZonalDataPoly(src, trg, srs=proj_utm)
# dump to file
zd.dump_vector('test_zonal_poly_cart')
# Create instance of type ZonalStatsPoint from zonal data object
obj3 = wrl.zonalstats.ZonalStatsPoly(zd)
t2 = dt.datetime.now()
t3 = dt.datetime.now()
# Create instance of type ZonalStatsPoly from zonal data file
obj3 = wrl.zonalstats.ZonalStatsPoly('test_zonal_poly_cart')
# Compute stats for target polygons
avg3 = obj3.mean(ds_clip.SF.values.ravel())
var3 = obj3.var(ds_clip.SF.values.ravel())
t4 = dt.datetime.now()
print("Approach #2 computation time:")
print("\tCreate object from scratch: %f "
"seconds" % (t2 - t1).total_seconds())
print("\tCreate object from dumped file: %f "
"seconds" % (t4 - t3).total_seconds())
print("\tCompute stats using object: %f "
"seconds" % (t3 - t2).total_seconds())
Approach #2 computation time:
Create object from scratch: 0.227418 seconds
Create object from dumped file: 0.078643 seconds
Compute stats using object: 0.000033 seconds
[17]:
# PLOTTING Approach #2
# Plot average rainfall and original data
testplot(ds.SF, obj3, col="mean",
title="Catchment rainfall mean (ZonalStatsPoly)")
[18]:
testplot(ds.SF, obj3, col="var",
levels=np.arange(0, np.max(var3), 1.),
title="Catchment rainfall variance (ZonalStatsPoly)")
[19]:
# Illustrate results for an example catchment i
i = 6 # try e.g. 5, 2
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, aspect="equal")
# Grid cell patches
src_index = obj3.zdata.get_source_index(i)
trg_patch = obj3.zdata.src.get_data_by_idx(src_index, mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="black")
# Target polygon patches
trg_patch = obj3.zdata.trg.get_data_by_idx([i], mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="red", linewidth=2)
# intersections
isecs1 = obj3.zdata.dst.get_data_by_att(attr="trg_index", value=[i], mode="geo")
isecs1.plot(column="src_index", ax=ax, cmap=pl.cm.plasma, alpha=0.5)
cat = trg.get_data_by_idx([i])[0]
bbox = wrl.zonalstats.get_bbox(cat[..., 0], cat[..., 1])
pl.xlim(bbox["left"] - 2000, bbox["right"] + 2000)
pl.ylim(bbox["bottom"] - 2000, bbox["top"] + 2000)
pl.legend()
pl.title("Catchment #%d: Polygons considered for stats" % i)
No artists with labels found to put in legend. Note that artists whose label start with an underscore are ignored when legend() is called with no argument.
[19]:
Text(0.5, 1.0, 'Catchment #6: Polygons considered for stats')
[20]:
# Compare estimates
maxlim = np.max(np.concatenate((avg1, avg3)))
fig = pl.figure(figsize=(10, 8))
ax = fig.add_subplot(111, aspect="equal")
pl.scatter(avg1, avg3, edgecolor="None", alpha=0.5)
pl.xlabel("Average of points in or close to polygon (mm)")
pl.ylabel("Area-weighted average (mm)")
pl.xlim(0, maxlim)
pl.ylim(0, maxlim)
pl.plot([-1, maxlim + 1], [-1, maxlim + 1], color="black")
pl.show()
Zonal Stats Polar Grid¶
[21]:
def create_center_coords(ds, proj=None):
# create polar grid centroids in GK2
center = wrl.georef.spherical_to_centroids(ds.range.values,
ds.azimuth.values,
0.5,
(ds.longitude.values, ds.latitude.values, ds.altitude.values),
proj=proj)
ds = ds.assign_coords({"xc": (["azimuth", "range"], center[..., 0]),
"yc": (["azimuth", "range"], center[..., 1]),
"zc": (["azimuth", "range"], center[..., 2])})
return ds
[22]:
filename = wrl.util.get_wradlib_data_file('hdf5/rainsum_boxpol_20140609.h5')
ds = xr.open_dataset(filename)
ds = ds.rename_dims({"phony_dim_0": "azimuth", "phony_dim_1": "range"})
ds = ds.assign_coords({"latitude": ds.data.Latitude,
"longitude": ds.data.Longitude,
"altitude": 99.5,
"azimuth": ds.data.az,
"range": ds.data.r,
"sweep_mode": "azimuth_surveillance",
"elevation": 0.5}
)
ds = ds.pipe(wrl.georef.georeference_dataset, proj=proj_utm)
ds = ds.pipe(create_center_coords, proj=proj_utm)
display(ds)
<xarray.Dataset> Dimensions: (azimuth: 360, range: 1000) Coordinates: (12/16) latitude float64 50.73 longitude float64 7.072 altitude float64 99.5 * azimuth (azimuth) float64 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 * range (range) float64 100.0 200.0 300.0 ... 9.98e+04 9.99e+04 1e+05 sweep_mode <U20 'azimuth_surveillance' ... ... gr (azimuth, range) float64 99.98 200.0 ... 9.986e+04 9.996e+04 rays (azimuth, range) float64 0.5 0.5 0.5 0.5 ... 359.5 359.5 359.5 bins (azimuth, range) float64 100.0 200.0 300.0 ... 9.99e+04 1e+05 xc (azimuth, range) float64 3.639e+05 3.639e+05 ... 3.657e+05 yc (azimuth, range) float64 5.622e+06 5.622e+06 ... 5.722e+06 zc (azimuth, range) float64 100.0 100.9 ... 1.558e+03 1.56e+03 Data variables: data (azimuth, range) float64 ...
[23]:
# reshape
shpfile = wrl.util.get_wradlib_data_file('shapefiles/agger/agger_merge.shp')
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
bbox = trg.extent
# create catchment bounding box
buffer = 5000.
bbox = dict(left=bbox[0] - buffer, right=bbox[1] + buffer,
bottom=bbox[2] - buffer, top=bbox[3] + buffer)
[24]:
ds_clip = ds.where((((ds.yc > bbox['bottom']) & (ds.yc < bbox['top'])) &
((ds.xc > bbox['left']) & (ds.xc < bbox['right']))), drop=True)
display(ds_clip)
<xarray.Dataset> Dimensions: (azimuth: 86, range: 695) Coordinates: (12/16) latitude float64 50.73 longitude float64 7.072 altitude float64 99.5 * azimuth (azimuth) float64 0.5 1.5 2.5 3.5 4.5 ... 82.5 83.5 84.5 85.5 * range (range) float64 2.8e+03 2.9e+03 3e+03 ... 7.21e+04 7.22e+04 sweep_mode <U20 'azimuth_surveillance' ... ... gr (azimuth, range) float64 2.799e+03 2.899e+03 ... 7.217e+04 rays (azimuth, range) float64 0.5 0.5 0.5 0.5 ... 85.5 85.5 85.5 85.5 bins (azimuth, range) float64 2.8e+03 2.9e+03 ... 7.21e+04 7.22e+04 xc (azimuth, range) float64 3.64e+05 3.64e+05 ... 4.359e+05 yc (azimuth, range) float64 5.624e+06 5.624e+06 ... 5.625e+06 zc (azimuth, range) float64 124.1 124.9 ... 1.034e+03 1.036e+03 Data variables: data (azimuth, range) float64 nan nan nan nan nan ... nan nan nan nan
[25]:
radar_utmc = np.dstack([ds_clip.xc, ds_clip.yc]).reshape(-1, 2)
radar_utmc.shape
[25]:
(59770, 2)
[26]:
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
src = wrl.io.VectorSource(radar_utmc, srs=proj_utm, name="src")
[27]:
###########################################################################
# Approach #1: Assign grid points to each polygon and compute the average.
#
# - Uses matplotlib.path.Path
# - Each point is weighted equally (assumption: polygon >> grid cell)
# - this is quick, but theoretically dirty
# - for polar grids a range-area dependency has to be taken into account
###########################################################################
t1 = dt.datetime.now()
# Create instance of type ZonalDataPoint from source grid and
# catchment array
zd = wrl.zonalstats.ZonalDataPoint(src, trg, srs=proj_utm,
buf=500.)
# dump to file
zd.dump_vector('test_zonal_points')
# Create instance of type ZonalStatsPoint from zonal data object
obj1 = wrl.zonalstats.ZonalStatsPoint(zd)
isecs1 = obj1.zdata.isecs
t2 = dt.datetime.now()
t3 = dt.datetime.now()
# Create instance of type ZonalStatsPoint from zonal data file
obj1 = wrl.zonalstats.ZonalStatsPoint('test_zonal_points')
# Compute stats for target polygons
avg1 = obj1.mean(ds_clip.data.values.ravel())
var1 = obj1.var(ds_clip.data.values.ravel())
t4 = dt.datetime.now()
print ("Approach #1 computation time:")
print(
"\tCreate object from scratch: %f seconds" % (t2 - t1).total_seconds())
print(
"\tCreate object from dumped file: %f seconds" % (t4 - t3).total_seconds())
print(
"\tCompute stats using object: %f seconds" % (t3 - t2).total_seconds())
Approach #1 computation time:
Create object from scratch: 3.706262 seconds
Create object from dumped file: 1.263752 seconds
Compute stats using object: 0.000042 seconds
[28]:
# PLOTTING Approach #2
src1 = wrl.io.VectorSource(radar_utmc, srs=proj_utm, name="src")
trg1 = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
# Just a test for plotting results with zero buffer
zd = wrl.zonalstats.ZonalDataPoint(src1, trg1, buf=0)
# Create instance of type ZonalStatsPoint from zonal data object
obj2 = wrl.zonalstats.ZonalStatsPoint(zd)
obj2.zdata.trg.set_attribute("mean", avg1)
obj2.zdata.trg.set_attribute("var", var1)
isecs2 = obj2.zdata.isecs
[29]:
# Illustrate results for an example catchment i
i = 0 # try e.g. 5, 2
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, aspect="equal")
# Target polygon patches
trg_patch = obj2.zdata.trg.get_data_by_idx([i], mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="black", linewidth=2)
trg_patch = obj1.zdata.trg.get_data_by_idx([i], mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="grey", linewidth=2)
# pips
sources = obj1.zdata.src.geo
sources.plot(ax=ax, label="all points", c="grey", markersize=200)
isecs1 = obj2.zdata.dst.get_data_by_att(attr="trg_index", value=[i], mode="geo")
isecs1.plot(ax=ax, label="buffer=0 m", c="green", markersize=200)
isecs2 = obj1.zdata.dst.get_data_by_att(attr="trg_index", value=[i], mode="geo")
isecs2.plot(ax=ax, label="buffer=500 m", c="red", markersize=50)
cat = trg.get_data_by_idx([i])[0]
bbox = wrl.zonalstats.get_bbox(cat[..., 0], cat[..., 1])
pl.xlim(bbox["left"] - 2000, bbox["right"] + 2000)
pl.ylim(bbox["bottom"] - 2000, bbox["top"] + 2000)
pl.legend()
pl.title("Catchment #%d: Points considered for stats" % i)
[29]:
Text(0.5, 1.0, 'Catchment #0: Points considered for stats')
[30]:
# Plot average rainfall and original data
testplot(ds_clip.data, obj2, col="mean",
title="Catchment rainfall mean (ZonalStatsPoint)")
[31]:
testplot(ds_clip.data, obj2, col="var", levels=np.arange(0, 20, 1.0),
title="Catchment rainfall variance (ZonalStatsPoint)")
[32]:
radar_utm = wrl.georef.spherical_to_polyvert(ds.range.values,
ds.azimuth.values,
0.5,
(ds.longitude.values, ds.latitude.values, ds.altitude.values),
proj=proj_utm)
radar_utm.shape = (360, 1000, 5, 3)
ds = ds.assign_coords({"xp": (["azimuth", "range", "verts"], radar_utm[..., 0]),
"yp": (["azimuth", "range", "verts"], radar_utm[..., 1]),
"zp": (["azimuth", "range", "verts"], radar_utm[..., 2])})
display(ds)
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
bbox = trg.extent
# create catchment bounding box
buffer = 5000.
bbox = dict(left=bbox[0] - buffer, right=bbox[1] + buffer,
bottom=bbox[2] - buffer, top=bbox[3] + buffer)
ds_clip = ds.where((((ds.yc > bbox['bottom']) & (ds.yc < bbox['top'])) &
((ds.xc > bbox['left']) & (ds.xc < bbox['right']))), drop=True)
display(ds_clip)
<xarray.Dataset> Dimensions: (azimuth: 360, range: 1000, verts: 5) Coordinates: (12/19) latitude float64 50.73 longitude float64 7.072 altitude float64 99.5 * azimuth (azimuth) float64 0.5 1.5 2.5 3.5 ... 356.5 357.5 358.5 359.5 * range (range) float64 100.0 200.0 300.0 ... 9.98e+04 9.99e+04 1e+05 sweep_mode <U20 'azimuth_surveillance' ... ... xc (azimuth, range) float64 3.639e+05 3.639e+05 ... 3.657e+05 yc (azimuth, range) float64 5.622e+06 5.622e+06 ... 5.722e+06 zc (azimuth, range) float64 100.0 100.9 ... 1.558e+03 1.56e+03 xp (azimuth, range, verts) float64 3.639e+05 ... 3.648e+05 yp (azimuth, range, verts) float64 5.622e+06 ... 5.721e+06 zp (azimuth, range, verts) float64 99.56 100.4 ... 1.559e+03 Dimensions without coordinates: verts Data variables: data (azimuth, range) float64 ...
<xarray.Dataset> Dimensions: (azimuth: 86, range: 695, verts: 5) Coordinates: (12/19) latitude float64 50.73 longitude float64 7.072 altitude float64 99.5 * azimuth (azimuth) float64 0.5 1.5 2.5 3.5 4.5 ... 82.5 83.5 84.5 85.5 * range (range) float64 2.8e+03 2.9e+03 3e+03 ... 7.21e+04 7.22e+04 sweep_mode <U20 'azimuth_surveillance' ... ... xc (azimuth, range) float64 3.64e+05 3.64e+05 ... 4.359e+05 yc (azimuth, range) float64 5.624e+06 5.624e+06 ... 5.625e+06 zc (azimuth, range) float64 124.1 124.9 ... 1.034e+03 1.036e+03 xp (azimuth, range, verts) float64 3.64e+05 3.64e+05 ... 4.358e+05 yp (azimuth, range, verts) float64 5.624e+06 ... 5.626e+06 zp (azimuth, range, verts) float64 123.6 124.5 ... 1.035e+03 Dimensions without coordinates: verts Data variables: data (azimuth, range) float64 nan nan nan nan nan ... nan nan nan nan
[33]:
radar_utm = np.stack([ds_clip.xp, ds_clip.yp], axis=-1).reshape(-1, 5, 2)
print(radar_utm.shape)
src = wrl.io.VectorSource(radar_utm, srs=proj_utm, name="src")
trg = wrl.io.VectorSource(shpfile, srs=proj_utm, name="trg", projection_source=proj_gk2)
(59770, 5, 2)
[34]:
###########################################################################
# Approach #2: Compute weighted mean based on fraction of source polygons
# in target polygons
#
# - This is more accurate (no assumptions), but probably slower...
###########################################################################
t1 = dt.datetime.now()
# Create instance of type ZonalDataPoly from source grid and
# catchment array
zd = wrl.zonalstats.ZonalDataPoly(src, trg, srs=proj_utm)
# dump to file
zd.dump_vector('test_zonal_poly')
# Create instance of type ZonalStatsPoint from zonal data object
obj3 = wrl.zonalstats.ZonalStatsPoly(zd)
obj3.zdata.dump_vector('test_zonal_poly')
t2 = dt.datetime.now()
t3 = dt.datetime.now()
# Create instance of type ZonalStatsPoly from zonal data file
obj4 = wrl.zonalstats.ZonalStatsPoly('test_zonal_poly')
avg3 = obj4.mean(ds_clip.data.values.ravel())
var3 = obj4.var(ds_clip.data.values.ravel())
t4 = dt.datetime.now()
print ("Approach #2 computation time:")
print(
"\tCreate object from scratch: %f seconds" % (t2 - t1).total_seconds())
print(
"\tCreate object from dumped file: %f seconds" % (t4 - t3).total_seconds())
print(
"\tCompute stats using object: %f seconds" % (t3 - t2).total_seconds())
obj3.zdata.trg.dump_raster('test_zonal_hdr.nc', 'netCDF', 'mean',
pixel_size=100.)
obj3.zdata.trg.dump_vector('test_zonal_shp')
obj3.zdata.trg.dump_vector('test_zonal_json.geojson', 'GeoJSON')
# Target polygon patches
trg_patches = [patches.Polygon(item, True) for item in obj3.zdata.trg.data]
Approach #2 computation time:
Create object from scratch: 2.922166 seconds
Create object from dumped file: 1.180934 seconds
Compute stats using object: 0.000038 seconds
[35]:
ds_clip.data.plot(x="x", y="y")
[35]:
<matplotlib.collections.QuadMesh at 0x7fb9c30edcc0>
[36]:
# Plot average rainfall and original data
testplot(ds_clip.data, obj4, col="mean",
title="Catchment rainfall mean (PolarZonalStatsPoly)")
[37]:
testplot(ds_clip.data, obj4, col="var", levels=np.arange(0, 20, 1.0),
title="Catchment rainfall variance (PolarZonalStatsPoly)")
[38]:
# Illustrate results for an example catchment i
i = 0 # try e.g. 5, 2
fig = pl.figure(figsize=(10,8))
ax = fig.add_subplot(111, aspect="equal")
# Grid cell patches
src_index = obj3.zdata.get_source_index(i)
trg_patch = obj3.zdata.src.get_data_by_idx(src_index, mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="black")
# Target polygon patches
trg_patch = obj3.zdata.trg.get_data_by_idx([i], mode="geo")
trg_patch.plot(ax=ax, facecolor="None", edgecolor="red", linewidth=2)
# intersections
isecs1 = obj3.zdata.dst.get_data_by_att(attr="trg_index", value=[i], mode="geo")
isecs1.plot(column="src_index", ax=ax, cmap=pl.cm.plasma, alpha=0.5)
cat = trg.get_data_by_idx([i])[0]
bbox = wrl.zonalstats.get_bbox(cat[..., 0], cat[..., 1])
pl.xlim(bbox["left"] - 2000, bbox["right"] + 2000)
pl.ylim(bbox["bottom"] - 2000, bbox["top"] + 2000)
pl.legend()
pl.title("Catchment #%d: Polygons considered for stats" % i)
No artists with labels found to put in legend. Note that artists whose label start with an underscore are ignored when legend() is called with no argument.
[38]:
Text(0.5, 1.0, 'Catchment #0: Polygons considered for stats')
[39]:
# Compare estimates
maxlim = np.max(np.concatenate((avg1, avg3)))
fig = pl.figure(figsize=(10, 8))
ax = fig.add_subplot(111, aspect="equal")
pl.scatter(avg1, avg3, edgecolor="None", alpha=0.5)
pl.xlabel("Average of points in or close to polygon (mm)")
pl.ylabel("Area-weighted average (mm)")
pl.xlim(0, maxlim)
pl.ylim(0, maxlim)
pl.plot([-1, maxlim + 1], [-1, maxlim + 1], color="black")
pl.show()